Fluid sensor



June 30, 1970 H. D. OGREN 3,517,545

FLUID SENSOR Original Filed Jan. 5, 1966 FIG. 3

NVENTOR. HAR 0. OGREN ATTORNEY United States Patent Oifice 3,517,545Patented June 30, 1970 3,517,545 FLUID SENSOR Harvey D. Ogren, St. Paul,Minn., assignor to Honeywell Inc., Minnneapolis, Minn., a corporation ofDelaware Original application Jan. 3, 1966, Ser. No. 518,155, now

Patent No. 3,435,688. Divided and this application Feb.

19, 1968, Ser. No. 706,348

Int. Cl. Glb 13/00 US. Cl. 73--37.5 2 Claims ABSTRACT OF THE DISCLOSUREA displacement sensor which provides a fluid output signal indicative ofthe magnitude and direction of displacement between two members. Thefluid flow through a pair of apertures is controlled by a pickoflfelement mounted on a member whose displacment is to be sensed. Thepickoff element controls the flow of fluid through the apertures so asto develop a fluid flow or fluid pressure output signal therein.

CROSS REFERENCE TO RELATED APPLICATION This application is a division ofco-pending application Ser. No. 518,155, filed Jan. 3, 1966, now Pat.No. 3,435,688.

BACKGROUND OF THE INVENTION This invention pertains to a displacementsensor providing the fluid output signal indicative of the magnitude indirection of displacement between two members.

SUMMARY OF THE INVENTION The applicant has provided a unique fluiddisplacement sensor having high reliability and accuracy at a low cost.The fluid displacement sensor provides a linear fluid output signal overthe range of its operation. In addition, the applicants fluiddisplacement sensor exerts negligible torquing upon the member whosedisplacement is being sensed. The fluid output signal can be directlyinterfaced with other fluid control devices, such as pure fluidamplifiers, in complete fluid systems without the need of additionalinterfacing devices.

In one particular embodiment, the applicants fluid displacement sensorcomprises a pair of apertures located within a housing means adapted tobe connected to a fluid source. The member whose displacement is to besensed is mounted for displacement relative to an axis. A pickoflelement is mounted on the member contiguous to the aperture so as tocontrol the fluid flow therethrough. Displacement of the member relativeto the axis causes relative movement between the pickotf element and theaperture so as to create a fluid output signal (pressure p or flow) inthe aperture indicative of the amount and direction of displacement.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross-sectional view of anattitude sensor utilizing the applicants fluid displacement sensor;

FIG. 2 is a cross-sectional view taken along line 22 of FIG. 1; and

FIG. 3 is a cross-sectional view of another embodiment of the applicantsinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2,reference numeral 10 generally depicts an attitude sensor. Attitudesensor 10 includes a housing means 11 having a central portion 12, anupper end cap 13, and a lower end cap 14. Central portion 12, and endcaps 13 and 14 cooperate to define a chamber in housing means 11.

A spherical rotor means is positioned within chamber 20 in housing means11. Rotor means 30 is hydrostatically supported within chamber 20 forrotation about three intersecting axes, for example axes 31, 32, 33, bymeans of a plurality of hydrostatic bearing pads 35. Hydrostatic bearingpads are adapted to be connected to a fluid source through supplypassage 36 in housing means 11.

Means 40 are provided for rotating rotor 30 about spin axis 32. Means 40comprises a fluid supply chamber 41 having a sintered metal ring 42around a periphery thereof. Fluid is supplied from supply passage 36through sintered ring 42, chamber 41, and through an opening in rotormeans '30 into a chamber therein. The fluid exhausts from the chamberwithin rotor means 30 through tangential exhaust ducts in the rotor. Afluid exhaust passage 44 is provided in housing means 11 to allow fluidto exhaust from chamber 20.

As is best illustrated in FIG. 2, housing means 11 has a first pair ofapertures 25, 26, and a second pair of apertures 27, 28 therein.Apertures 25-28 are in communication with chamber 20. The apertures maybe connected to means for determining the magnitude and sense of thefluid flow or pressure dilferential therein. For example, apertures 25and 26 may be connected to the control ports of a first proportionalpure fluid amplifier 38 and apertures 27 and 28 may be connected to thecontrol ports of a second proportional pure fluid amplifier. It is notnecessary that the apertures be connected to a fluid amplifier; othermeans for sensing the fluid flow and pressure differential may beutilized.

Rotor means 30 has a pickofl element mounted thereon. In the particularembodiment illustrated, pickofi element 50 is formed integral with rotor30 by forming an annular recess 51 in the surface of rotor means 30.Pickotf element 50 is positioned upon rotor means 30 contiguous toapertures 25 through 28 so as to control the flow of fluid therethrough.In the particular embodiment illustrated, apertures 25 through 28 areequally angularly spaced about axis 32. When rotor means 30 is in thenull position as illustrated in FIGS. 1 and 2, pickoff element 50 coverseach of the apertures in equal amount so as to allow the same amount offluid flow through each aperture.

In operation, supply passage 36 is connected to a source of fluid androtor means 30 is supported in chamber 20 for rotation about axes 31,32, 33. Fluid also flows into the chamber in rotor means 30 and exhauststhrough the tangential nozzles so as to rotate rotor means 30 about axis32 at a substantially constant angular velocity. A portion of the fluidsupplied to chamber 20 exhausts through apertures 25 through 28. Withrotor means 30 in the null position as illustrated in FIGS. 1 and 2,pickoff element 50 allows equal fluid flow through each of theapertures. The fluid flow through the apertures is a portion of thefluid flowing into chamber 20 through bearing pads 35 and ring 42. Inthe null condition, there is no pressure or flow differential betweenapertures 25 and 26 or between apertures 27 and 28. However, if rotormeans 30 rotates about axis 33 relative to housing means 11, in aclockwise direction as viewed in FIG. 1, pickofl element 50 will covermore of aperture 25 than of aperture 26. This results in a fluid signalindicative of the direction and magnitude of displacement of rotor means30 about axis 33. For example, if greater fluid flow is allowed throughaperture 26 than through aperture 25, the magnitude of the diflerence inflnid flow is indicative of the magnitude of displacement of rotor means30 about axis 33 and the sense of the fluid flow displacement indicatesthe direction of displacement. In some embodiments, it is desirable tomeasure the pressures in apertures 25 and 26 in which case the magnitudeof the pressure difi'erential is indicative of the magnitude of rotationand the sense of the pressure differential is indicative of thedirection of rotation of rotor means 30 about axis 33. The fluid signalmay be used directly in a fluid system or means such as a fluidamplifier can be utilized to determine the magnitude and sense of thefluid signal.

Apertures 27 and 28 function in a similar manner to provide a fluidsignal indicative of the amount and direction of rotation of rotor means30 about axis 31 relative to housing means 11.

It should be pointed out that the applicants unique fluid sensor is notlimited to the particular two axis embodiment illustrated and may beutilized as a single axis sensor. Furthermore, the applicants uniquefluid sensor is not limited to sensing rotational displacement asillustrated in FIGS. 1 and 2. It is within the scope of the applicantsinvention to utilize a single aperture in conjunction with the pickoffelement so as to provide a fluid output signal indicative of thedisplacement of the pickoif element relative to the aperture.

Referring now to FIG. 3, an alternate embodiment of the applicantsunique fluid displacement sensor is illustrated. The embodimentillustrated in FIG. 3 functions to sense displacement along as axis. Ahousing means 60 is provided having an aperture 62 and an aperture 63therein. Apertures 62 and 63 are positioned along an axis 64. Aperture62 is adapted to be connected to a fluid source by means of a passage 65having a fluid restrictor 66 therein. Aperture 63 is adapted to beconnected to a fluid source through a passage 67 having a fluid resistor68 therein.

A member 70 is mounted upon housing means 60 by means such as bearings71 for displacement along axis 64 relative to housing means 60. Apickofl element 75 is mounted upon member 70 contiguous to apertures 62and 63 so as to control the flow of fluid therethrough. In the nullposition, as illustrated in FIG. 3, pickoff element 75 covers equalportions of apertures 62 and 63 so as to allow equal flow through eachaperture.

In operation, apertures 62 and 63 are connected to a fluid source bymeans of passages 65 and 67. Fluid flows from the fluid source into theapertures; a portion of the fluid flows out of the apertures pastpickoff element 75. The remainder of the fluid flows out the other endof the apertures which may be connected to a fluid amplifier if sodesired. The arrows in FIG. 3 illustrate the fluid flow through theapertures. Pickoff element 75 functions to restrict the flow of fluidthrough the apertures thereby causing a fluid signal (pressure or fluidflow) to be developed therein indicative of the magnitude and directionof displacement. Fluid restrictions 66 and 68 function to provide afixed resistance in supply passages 65 and 67.

At the null position of member 70, there is equal fluid flow and equalpressure in the apertures 62 and 63. Upon displacement of element 70along axis 64, pickoif element 75 will allow greater fluid flow in oneaperture than in the other. The diflerence in fluid flow (or pressure)is indicative of the amount of displacement of member 70 relative tohousing means 60. The sense of the fluid flow (or pressure) differentialis indicative of the direction of displacement element 70 along axis 64relative to housing means 60. The fluid signal in the apertures can beused directly or means such as a fluid amplifier may be utilized todetermine the magnitude and sense of the fluid signal.

The applicant has provided unique fluid displacement sensor that ishighly reliable and at the same time relatively inexpensive.

While I have shown and described the specific embodiments of thisinvention, further modifications and improvements will occur to thoseskilled in the art. I desire to be understood, therefore, that thisinvention is not limited to the particular form shown.

What I claim is:

1. A fluid displacement sensor comprising:

housing means;

a first and second pair of apertures within said housing means adaptedto be connected to a fluid source;

a member mounted on said housing for displacement relative to a firstand a second axis; and

a pickofl element mounted on said member, said pickofl element beingcontiguous to said first and second pair of apertures so as to controlthe fluid flow through each of the apertures, whereby said first pair ofapertures provides a fluid signal indicative of the amount and directionof displacement of said member relative to said first axis and saidsecond pair of apertures provides a fluid signal indicative of theamount and direction of displacement of said member relative to saidsecond axis.

2. A fluid displacement sensor comprising:

housing means;

a pair of apertures Within said housing means adapted to be connected toa fluid source;

a member mounted on said housing for displacement relative to an axis;and

a pickoff element mounted on said member, said pickofl element beingcontiguous to said pair of apertures so as to control the fluid flowtherethrough, the displacement of said member relative to said axiscausing movement between said .pickofr" element and said pair ofapertures developing a fluid signal in said pair of apertures indicativeof the magnitude and direction of displacement of said member about saidaxis.

References Cited UNITED STATES PATENTS 2,397,494 4/1946 Kuppersmith33147 FOREIGN PATENTS 879,985 10/ 1961 Great Britain.

LOUIS R. PRINCE, Primary Examiner W. A. HENRY II, Assistant Examiner

